Security update MS15-011 & MS15-014 installed which hardens the UNC paths for SYSVOL & NETLOGON & the following registry keys being pushed using group policy:

  • RequirePrivacy=1
  • RequireMutualAuthentication=1
  • RequireIntegrity=1

Other related article: https://blogs.technet.microsoft.com/askds/2016/06/22/deploying-group-policy-security-update-ms16-072-kb3163622/